UNIT 10 Rock Mass Classification Rock Mass Classification

UNIT 10 Rock Mass Classification 骚一骚 更精彩 Rock Mass Classification Urban Underground Space Engineering Hebei University of Engineering 新浪微博 @努力hard Class 12 -02 Group 1 微信公众号 Hard. PPT 演界网店铺 Hard. PPT

New Words and Expressions 先看单词或短语 Refer to P 92 span Additions spall blast stress field bench rock brust heading / face steel sets slab RMR NATM civil engineering parameter shot crete RQD rockbolt wire mesh

What Why How Who 怎么阅读 For Example It is important to understand that design the usestages of a rock classification ①①[During the feasibility and preliminary of a mass project , when very LET’S GO scheme does not ( and canonnotthe ) replace someand of the design little detailed information rock mass its more stress elaborate and hydrologic procedures. However，② the use of of athese procedures requires access characteristics is available], the rock design mass classification scheme can be to of relatively detailed information in situ stress， rock mass properties and planned considerable benefit. ② At itson simplest, this may involve using the classification excavation of that which be available at an in the scheme as asequence， check-list tonone ensure all may relevant information hasearly beenstage considered. project. ③other As this becomes available， of the rock mass ③ At the end information of the spectrum, one or more rock the massuse classification schemes should be updated and used in conjunction with siteofspecific can be used to build up a picture of the composition and characteristics a rock analyses. mass to provide initial estimates of support requirements, and to provide estimates of strength and deformation properties of the rock mass.

Part One Engineering Rock Mass Classification 程岩体分类 P 88 -89

Engineering Rock Mass Classification 程岩体分类 Introductions 读前介绍

Part Two Terzaghi’s Rock Mass Classification 太沙基岩体分类 P 89 -90

Descriptions 相关描述 Crushed but Moderately Blocky Squeezing Stratified Swelling Intact and Jointed Seamy Rock Chemically Rock 块中 状、有 完胀 层 度 挤 膨 整Intact 状 节 压 裂 理缝 岩 岩岩 碎 片 岩（未 受 化 学 扰 动）

Part Three Classifications Involving Stand-up Time 隧洞自稳时间分类 P 90

Several Concepts 几个概念 1 Unsupported span 无支护跨度 max(span of tunnel, distance between the face and the nearest support) 2 NATM 新奥法 New Austrian Tunneling Method

Several Arguments 几个观点 a The stand–up time for an unsupported span is related to the quality of the rock mass in with the span is excavated. b An increase in the span of the tunnel leads to a significant reduction in the time available for the installation of support. c NATM includes a number of techniques for safe tunneling in rock conditions in which the stand-up time is limited before failure occurs. d In designing support for hard rock excavations it is prudent to assume that the stability of the rock mass surrounding the excavation is not time –dependent.

Part Four Rock Quality Designation Index (RQD ) 岩 石 质 量 指 标 （R Q D 值） P 90 -91

RQD 什么是RQD A Purpose 目的 Quantitative estimate 提供一种数值评价方法 B Definition 定义 Percent of pieces longer than 100 mm 大于100 mm岩心长度百分比 C Measure 方法 At least NW size double-tube core barrel 标准尺寸(直径54. 7 mm) 双层岩心管

Calculation 计算方法 60. 0 For example Try a try 17. 0 5. 0 Length of core run : 200 10. 0 cm RQD = ( 38 + 17 + 20 +35 ) / 36. 0 200 × 100 % = 55 % 3. 0 17. 0 15. 0 1. 0 38. 0 Length of core run : 200 cm RQD = 20. 0 = ( 60 + 36 + 17 + 1 ) / 200 × 100 % 60+36+17+15 35. 0 = ( 6644 ) %

Calculation 计算方法 Palmstrom’s relationship for clay-free rock masses（ 不 含 粘 性 土 的 岩 体 ） RQD = 115 − 3. 3 Jv Jv ——for the sum of the number of joints per unit length for all joint ！ Changed by the borehole orientation Use volumetric joint count to reduce this dependence.

Attention 注意事项 1 Deere’s RQD—— When using diamond drill core, care must be taken to ensure that fractures caused by handing or the drilling process, are identified and ignored. 2 Palmstrom’s RQD—— For exposure mapping, blast induced fractures should not be included when estimating Jv.

Conclusion RQD总结 North America（北美） Deere’s RQD has been widely used, particularly in North America, for the past 25 years. Some attempted to relate RQD to Terzaghi’s rock load factors and to rock bolt requirements in tunnels. The Most Important Use of RQD is A Component of the RMR.

UNIT 10 Rock Mass Classification 骚一骚 更精彩 THANK YOU Urban Underground Space Engineering 新浪微博 @努力hard 微信公众号 Hard. PPT 演界网店铺 Hard. PPT